Aaron71771

I was on my way to Grandma's on Saturday to put the car awar for storage. I got about a mile down the road and the clutch pedal would only go down about 2/3's of the way :( I go the car home and initially thought it was something with the pedal. So I removed the retaining clip that connect the pedal to the clutch master and found I had full pedal travel. Ok - next was to check the master. I pulled it off and found it to be in good working order. When I reconnected the master (but not the clutch fluid line) I found I had full pedal travel. So next was the cluth slave. I pulled it off and it too seems to be in good working order. So I put everything back togther - bleed the system and again had only 2/3's pedal travel.

I spent Sunday pulling the transmission off. I don't have the bell housing off yet (one rounded-off bolt to yet get off :cry :cry) but I do have a few questions. I just did this whole process this past spring when I replaced the clutch fork (old one was bent).

Would a completely extended slave cause this problem (hard pedal)?
It's possible that my fork is bent again after only 6 months, any ideas?
How thick is a new clutch?

I do know when I put the slave on there is virtually zero travel between it and the clutch fork; the slave rod fully extended just barely touches the fork. So I am thinking that my clutch is worn too thin. Any other ideas?

Atok

Sounds to me like the clutch is completely worn out or the fork bent again, probably the fork. I would think the clutch would slip before it wore that bad! Can you slide the fork off the ball stud and away from the release bearing? If the clutch is worn you probably won't be able to slide the fork back to get the bell housing off. Although a bent fork would probably have the same effect.

You say your slave just touches the fork. Something is wrong here. I must have at least an inch to compress the slave when I bolt it up. Also, with the slave unbolted from the bell housing you should have full pedal travel. The GM procedure for bleeding the slave says to unbolt it, hold it so the bleeder is facing up, push pedal to floor, open bleeder, close bleeder, release pedal.

G'luck!

SPD DMN

How are you bending forks? That would be my first question. Second, if you think it is a bent fork, then it would hit the pressure plate and generate a grinding noise when the clutch was all the way depressed (or at least as far as you could press it). I can not think of much else that would cause the pedal to simply quite travelling at 2/3 though. Only thing would be if the pilot bearing was somehow sticking on the input shaft housing of the transmission causing it to bind.

Atok

Good question. :)

Aaron71771

I wish I knew why the fork was bending. There is usually no noise from the trans/clutch when driving and the clutch is not slipping yet. A few times I noticed a quick "rasping" noise with letting the clutch out from a stop. Perhaps something is wrong with the pressure plate? I can move the clutch fork about 1/4~1/2 inch.

I do know that with the slave detached from the bell housing, and fully extended I still only have about 2/3 pedal travel - then a hard stop. However nothing in the clutch hydralics appear to have a problem, as best as I can tell that a normal thing when the slave is fully extended - has anyone else noticed this?

I don't have the bell housing off yet - look like I get to cut off the last bolt holding it on. :(

Can anyone tell me how thick a new clutch plate is?

SPD DMN

A new clutch plate should be about .310" thick at the material. However, the thickness of the disk should only move the activation point in the clutch travel up or down. When the disk starts to wear thin, it takes less pull of the pressure plate to release it so the clutch release point will be higher up (farther from the floor). If you can, use a caliper and a straight edge to determine how much pull you are getting on the pressure plate. You should be getting .400" or more. (I am currently fighting a similar issue where i am only getting .160" of throw when I press the pedal and I need .500" for my clutch.) If I read your above post right, the slave is not moving the clutch fork?

Aaron71771

Vette92,

I am getting less then 1/8" of travel out of the slave, and this is if I move the clutch fork so it makes contact. My clutch was releasing at the top of the pedal as well.

theadmiral94

:iagree:

on our 94 LT1/ZF6, last night I removed our clutch slave cylinder to butt-up-end-it and gravity bleed it. During removal and after re-install, I too had about 1" - 2 " of plunger travel which compressed as I pushed and then bolted the slave cylinder back in (it contacted the fork even before reaching the bolts). Whereas I don't know if ours is an AC Delco slave nor if it is original or replaced (car has 93K), or how similiar ours is to yours, I wonder if you have the correct slave cylinder or if it is working properly.

good luck... :flag

SPD DMN

Yeah, then something is wrong. I should have more info for you tomorrow as I am getting a new clutch master today to see if it fixes my problem. If it fixes my problem, then I would suspect you may have the same issue with a bad clutch master cylinder.

Aaron71771

Both the slave and the master are new. The slave matches the old one I pulled off the car back in the spring of this year. Even if the one of those were bad that would not fix the slave making almost zero contact with the fork. I have taken both of them apart to make sure, and they both are in good working order.

If you could do me a favor, I would appreciate it. After you bleed your slave please check your clutch pedal travel. This would be before you mount the slave on to the bell housing.

My thought is that when the system is installed and the slave fully extended and the system has been bleed fully, you can only get so much pedal travel before the clutch fluid won't compress anymore.

FullShred

Yesterday I put a brand new master and slave on my '90 L98. I found that with the slave not installed on the bell housing, it extends all the way - I assume there is a spring in it. Before I had the air bled out, the pedal would go all the way to the floor. After I got it bled ( maybe - see my question here
http://forums.corvetteforum.com/zerothread?id=693836

I found the pedal would move only an inch or so before stopping. This makes sense in my pea brain cause at first I was compressing the air, so the pedal went to the floor. After the air is out, the fluid can't compress and has nowhere to go since the slave is already fully extended.

Let us know what you find and good luck

Aaron71771

Well I got the bell housing off as well as the clutch. The clutch fork is not only bent at about a 40 degree angle, the metal is actually ripped :( The clutch itself is just under 1/4 thick. Not exactly sure why I have now bent two clutch forks in less then 7 months. I beleive that something may be wrong with the pressure spring. So, will be putting in a new clutch kit as well as a new clutch fork.

SPD DMN

Looks like we both found the problem to be the same. After putting in another new clutch master cylinder with the same results I looked for more areas that may be the issue and looked at the fork and it ws hosed. I did not notice it when I was checking the clutch out before because it was permanently mounted to my bellhousing because the bolt was seized.

Now why your are failing so quickly is a big problem. Is it a stock pressure plate?

Here is what mine looked like when I pulled it out...note I have clearanced the bottom of mine to clear an aftermarket setup, which I am sure contributed to my failure.

Aaron71771

As far as I can tell it's a stock valeo pressure plate. My fork looks a lot like yours. The first one I bent (this past Spring) was bent right up my the slave dimple. Are you putting in a new clutch/pressure plate? I've been thinking about takingmy new fork down and having some welding done to strengthen it... shouldn't have to tho. :(


Does the new clutch/pressue plate need to be balanced before install?

Atok

As far as I can remember, when I did mine I had full pedal travel with the slave not bolted to the clutch housing. I'm not sure how accurate my memory is....





[Modified by Atok, 8:40 AM 11/19/2003]

SPD DMN

I am putting in a McCleod dual disk clutch. The pressure plate has a lot more force than a stock one.

Any new pressure plate will be off a little, but you can bolt it right on without having to balance it.